Wednesday, September 28, 2011

ScienceDaily (Sep. 28, 2011)
— Production of crop milk, a secretion from the crops of parent birds,
is rare among birds and, apart from pigeons, is only found in flamingos
and male emperor penguins. Essential for the growth and development of
the young pigeon squab, pigeon 'milk' is produced by both parents from
fluid-filled cells lining the crop that are rich in fat and protein.

Research published in BioMed Central's open access journal BMC
Genomics uses new technology to study the genes and proteins involved in
pigeon 'milk' production and shows that pigeon 'milk' contains
antioxidants and immune-enhancing proteins.

Researchers from CSIRO Livestock Industries and Deakin University,
Australia, compared the global gene expression profiles of the crops of
four 'lactating' and four 'non-lactating' female pigeons. As the pigeon
genome has not yet been sequenced, they used a chicken microarray to
find the genes involved. Genes predominantly over-expressed in
'lactating' birds were those involved in stimulating cell growth,
producing antioxidants and in immune response. They also found genes
associated with triglyceride fat production, suggesting the fat in the
'milk' is derived from the pigeon's liver.

Lead author, Meagan Gillespie, says, "It is possible that if
antioxidant and immune proteins are present in pigeon 'milk', they are
directly enhancing the immune system of the developing squab as well as
protecting the parental crop tissue." She continues, "This study has
provided a snap-shot view of some of the processes occurring when
'lactation' in the pigeon crop is well established. Due to the unusual
nature of 'lactation' in the pigeon it would be interesting to
investigate the early stages of the differentiation and development of
the crop in preparation for 'milk' production to further ascertain gene
expression patterns that characterize crop development and 'lactation'
in the pigeon."

She concludes, "This mechanism is an interesting example of the
evolution of a system with analogies to mammalian lactation, as pigeon
'milk' fulfills a similar function to mammalian milk."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by BioMed Central, via EurekAlert!, a service of AAAS.

Tuesday, September 27, 2011

ScienceDaily (Sep. 26, 2011) — Nest-building is not just instinctive but is a skill that birds learn from experience, research suggests.

Scientists filmed male Southern Masked Weaver birds in Botswana as
they built multiple nests out of grass during a breeding season. Their
findings contrast with the commonly-held assumption among scientists
that nest-building is an innate ability.

The researchers found that individual birds varied their technique
from one nest to the next. They also saw that some birds build their
nests from left to right, and others from right to left.

Also, as the birds gained more experience in building nests, they
dropped blades of grass less often, implying that the art of nest
building requires learning.

Researchers from the Universities of Edinburgh, St Andrews and
Glasgow together with scientists from Botswana say their findings may
help to explain how birds approach nest-building and whether they have
the mental capacity to learn, or whether their skills are developed
through repetition.

Researchers chose the colourful African bird because they build
complex nests, which is potentially a sign of intelligence. More
importantly, Weaver birds build many nests -- often dozens in a season,
allowing the team to monitor differences in nests built by the same
bird.

Dr Patrick Walsh of the University of Edinburgh's School of
Biological Sciences, who took part in the study, said: "If birds built
their nests according to a genetic template, you would expect all birds
to build their nests the same way each time. However this was not the
case. Southern Masked Weaver birds displayed strong variations in their
approach, revealing a clear role for experience. Even for birds,
practice makes perfect."

The research was published in the journal Behavioural Processes and was funded by the Leverhume Trust.

University of Edinburgh (2011, September 26). Feathered friends are far from bird-brained when building nests. ScienceDaily. Retrieved September 27, 2011, from http://www.sciencedaily.com­/releases/2011/09/110925192704.htm

Thursday, September 22, 2011

Researchers
at U Chicago and the Chicago Zoological Society found in an experiment
at Brookfield Zoo that penguins can recognize the smell of familiar
locations, something that may guide them back to their mates. The
ability is useful as penguins live in large colonies but remain
monogamous.

Photos by Jim Schulz/Chicago Zoological Society

Smells may help birds identify their relatives

By William Harms

September 21, 2011

Birds may have a more highly developed sense of smell than researchers
previously thought, contend scholars who have found that penguins may
use smell to determine if they are related to a potential mate.

The research by the University of Chicago and the Chicago Zoological
Society, which manages Brookfield Zoo, shows how related birds are able
to recognize each other. The study, published Wednesday, Sept. 21 in the
article, “Odor-based Recognition of Familiar and Related Conspecifics: A
First Test Conducted on Captive Humboldt Penguins (Spheniscus
humboldti)” in the journal PLoS ONE, could help conservationists design
programs to help preserve endangered species.

“Smell is likely the primary mechanism for kin recognition to avoid
inbreeding within the colony,” said Heather Coffin, lead author of the
paper.

Coffin conducted the research while a graduate student at UChicago and
was joined in writing the paper by Jill Mateo, associate professor in
Comparative Human Development at UChicago, and Jason Watters, director
of animal behavior research for the Chicago Zoological Society.

“This is the first study to provide evidence for odor-based kin
discrimination in birds,” said Mateo, who is a specialist on kin
recognition.

Experts said the work offers important insights into how birds use smell to guide behavior.
“The work by the research group is truly groundbreaking in that it
shows for the first time ever in birds how the olfactory sense of
captive penguins is both informative and functional in a behaviorally
critical context: namely the recognition of friends from foes in
general, and relatives from non-relatives in particular,” said Mark E.
Hauber, professor of psychology at Hunter College, a specialist on bird
social recognition.

Penguins are ideal subjects because they typically live in colonies
made up of thousands of birds. They live in monogamous pairs — an
arrangement that facilitates rearing of their young, since parents
frequently take turns leaving the nest to gather food. Despite the size
of the community, mates are able to find each other after traveling for
days foraging for food in the ocean.

Research on other sea birds has shown that smell helps guide birds to
their home territory and helps them forage for food. Other research has
shown that birds could use sound and sight to recognize each other, but
no other studies have shown that smell might be used in connection with
kin recognition, Mateo said.
In the study conducted at Brookfield Zoo, researchers first sought to
determine if the penguins were able to recognize familiar individuals by
smell. They constructed an experiment using a dozen penguins, from a
group that included breeding pairs, their offspring and nonbreeding
individuals. The birds — all Humboldt penguins—endangered natives of
Peru—were from groups either on exhibit or off exhibit.

The zoo is an ideal setting for the research, as it has extensive
records on which penguins are related and have been housed together,
Watters said.

Researchers took odor samples from glands near the penguins’ tails,
where an oil that the birds use for preening is secreted. They put the
oil on cotton swabs and rubbed the odor inside dog kennels, similar to
the enclosures penguins at a zoo use for their nests. They also put the
odor on paper coffee filters and placed them under mats inside the
kennels.

When the penguins were released to the area containing the kennels, the
researchers found that penguins spent more time in the kennels with
familiar odors. The penguins were able to distinguish between the odors
of birds they spent time with and the odors of unfamiliar penguins.

“What I found particularly notable about the study was that the authors
identified the oil secreted from the penguins’ preen gland, which is
rubbed on the feathers to make them water repellent, as the odor source
used in recognition,” said Bryan D. Neff, professor and associate
chairof biology, University of Western Ontario and an expert on kin
recognition. “Oils are used in kin recognition by species of other
animals, most notably a variety of insect species, including bees and
wasps, which when considered with the penguin data provide a wonderful
example of convergent evolution.”

“It’s important for birds that live in large groups in the wild, like
penguins, to know who their neighbors are so that they can find their
nesting areas and also, through experience, know how to get along with
the birds nearby,” Watters said.

Because offspring usually return to the same colony for nesting,
siblings have the potential of becoming mates, something that can be
avoided by their smell mechanism, the new research shows.

Researchers also found that when the birds were exposed to the odors of
unfamiliar kin and unfamiliar non-kin, they spent more time in the
kennels with odors of unfamiliar non-kin, indicating they were probably
able to determine by smell which animals they were related to and were
more curious about the novel odors. Being able to make the distinction
may help the penguins avoid mating with kin, researchers said. The
discovery also could assist zoos in managing their breeding programs.

“It could also be true that birds do a better job determining who
potential mates are than do people in zoos, who spend a great deal of
time lining up the appropriate matches,” Watters said.

The ability of birds to be able to recognize familiar scents and thus
be guided to their home territory also has potential value to
naturalists, he said. “You could imagine that if you were trying to
reintroduce birds to an area, you could first treat the area with an
odor the birds were familiar with. That would make them more likely to
stay.

Wednesday, September 21, 2011

The bones are from the 17 species of Cretaceous birds which went
extinct around the time of the dinosaurs. The two on the far left are
foot bones and the rest are shoulder bones. (Credit: Courtesy Yale
University)

ScienceDaily (Sep. 21, 2011)
— A new study puts an end to the longstanding debate about how archaic
birds went extinct, suggesting they were virtually wiped out by the same
meteorite impact that put an end to dinosaurs 65 million years ago.

For decades, scientists have debated whether birds from the
Cretaceous period -- which are very different from today's modern bird
species -- died out slowly or were killed suddenly by the Chicxulub
meteorite. The uncertainty was due in part to the fact that very few
fossil birds from the end of this era have been discovered.

Now a team of paleontologists led by Yale researcher Nicholas
Longrich has provided clear evidence that many primitive bird species
survived right up until the time of the meteorite impact. They
identified and dated a large collection of bird fossils representing a
range of different species, many of which were alive within 300,000
years of the impact.

"This proves that these species went extinct very abruptly, in terms
of geological time scales," said Longrich. The study appears the week of
Sept. 19 in the journal Proceedings of the National Academy of Sciences.
The team examined a large collection of about two dozen bird fossils
discovered in North America -- representing a wide range of the species
that existed during the Cretaceous -- from the collections of Yale's
Peabody Museum of Natural History, the American Museum of Natural
History, the University of California Museum of Paleontology, and the
Royal Saskatchewan Museum. Fossil birds from the Cretaceous are
extremely rare, Longrich said, because bird bones are so light and
fragile that they are easily damaged or swept away in streams.

"The birds that had been discovered hadn't really been studied in a
rigorous way," Longrich said. "We took a much more detailed look at the
relationships between these bones and these birds than anyone had done
before."

Longrich believes a small fraction of the Cretaceous bird species
survived the impact, giving rise to today's birds. The birds he examined
showed much more diversity than had yet been seen in birds from the
late Cretaceous, ranging in size from that of a starling up to a small
goose. Some had long beaks full of teeth.
Yet modern birds are very different from those that existed during
the late Cretaceous, Longrich said. For instance, today's birds have
developed a much wider range of specialized features and behaviors, from
penguins to hummingbirds to flamingoes, while the primitive birds would
have occupied a narrower range of ecological niches.

"The basic bird design was in place, but all of the specialized
features developed after the mass extinction, when birds sort of
re-evolved with all the diversity they display today," Longrich said.
"It's similar to what happened with mammals after the age of the
dinosaurs."

Longrich adds that this study is not the first to suggest that
archaic birds went extinct abruptly. "There's been growing evidence that
these birds were wiped out at the same time as the dinosaurs," Longrich
said. "But this new evidence effectively closes the book on the
debate."

Other authors of the paper include Tim Tokaryk (Royal Saskatchewan Museum) and Daniel Field (Yale University).

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Yale University.

Friday, September 16, 2011

(Edmonton) Secrets from the age of the dinosaurs are usually
revealed by fossilized bones, but a University of Alberta research team
has turned up a treasure trove of late Cretaceous feathers, which have
been discovered trapped in tree resin.
The resin turned to resilient amber preserving some
80-million-year-old protofeathers, possibly from non-avian dinosaurs, as
well as plumage that is very similar to modern birds, including those
that can swim under water.

U of A paleontology graduate student Ryan McKellar discovered a wide range of feathers trapped in amber in collections at the Royal Tyrrell Museum and in the private collection of the Leuck family in Medicine Hat.
“Most of the feather specimens were probably blown into contact
with the sticky surface of the resin and encapsulated by subsequent
resin flows,” said McKellar.
The 11 feather specimens used by the U of A team were all found
near the community of Grassy Lake in southern Alberta. The research
specimens are described as the richest amber feather find from the late
Cretaceous period.

“The amber preserves microscopic detail of the feathers and even
their pigment or colour,” said McKellar. “I would describe the colours
as typically ranging from brown to black.”
During the late Cretaceous, southern Alberta was a warm coastal
region. “The trees that produced the resin were probably comparable to
the redwood forests of the Pacific Northwest,” said McKellar.
No dinosaur or avian fossils were found in direct association with
the amber feather specimens, but McKellar says comparison between the
amber and fossilized feathers found in rock strongly suggest that some
of the Grassy Lake specimens are from dinosaurs. The non-avian dinosaur
evidence points to small theropods as the source of the feathers.

McKellar says that some of the feather specimens can take on water,
enabling the bird to dive more effectively and are very similar to
those of modern birds like the Grebe, which are able to swim underwater.
“The preservation of microscopic detail and pigmentation has
provided a unique snapshot of feathers and their uses in the late
Cretaceous forests of Alberta,” said McKellar.

The U of A team’s research was published Sept. 15, in the journal Science.

Tuesday, September 13, 2011

King
penguin parents spend about 14 months incubating their egg, then
rearing their chick. They take it in turns to find food, so the strength
of their bond is crucial. Biologists want to know how they make this
important mate selection, and even how the birds tell a male from a
female; the two sexes look almost identical.

Prof Stephen Dobson from the National Centre for Scientific Research in
Montpellier, France, playfully sums up his research: "I'm trying to work
out what makes a sexy penguin." His studies of the birds on Kerguelen
Island have revealed that penguins often struggle to spot a member of
the opposite sex.

Prof Dobson also found that males on the island in the Southern Indian
Ocean often had to compete particularly hard to snag a female mate. He
and his team noticed that, during mating season, trios of penguins would
"parade" around together. DNA analysis showed that the trios were
usually two males pursuing a female.

When the penguins do find a mate that they take a shine to they carry
out an intimate dance – stretching their necks from side to side in what
appears to be an elaborate embrace. Occasionally, two males will engage
in this mating dance, but the pair usually separate when one finds a
female partner.

Prof Dobson’s team, which also includes researchers from the Centre for
Functional and Evolutionary Ecology in Montpellier, France, has found
that the penguins' bright yellow ear patches play an important role in
attraction.

The researchers measured the size and colour intensity of these ear
patches to find out how they affect penguin attractiveness. They also
used black hair dye to artificially reduce the size of the ear patches.

Males with artificially-reduced ear patches seemed to have less success
finding a female. Females also appeared to choose males with larger ear
patches, and the researchers think that larger ear patches might convey a
male's ability to defend his chick and his territory in the crowded
colony.

The scientists hope to unpick the evolutionary mystery of how these
birds select a suitable partner who will co-operate in the care of their
egg and chick. They also hope to find out more about the penguins'
natural behavior to see how they are being affected by environmental
change.

Wednesday, September 7, 2011

BirdLife species factsheet for Macaroni Penguin
Macaroni Penguin Eudyptes chrysolophus breeds in at least
216 colonies at 50 sites in the higher latitudes of the southern
hemisphere (Woehler 1993, Woehler and Croxall 1999). The total
population is estimated by BirdLife to be c.9 million pairs, although it
is argued that this is likely to be an underestimate because of
potential underestimates in the South Georgia Island region (USFWS
2008). The species is listed as Vulnerable under criteria A2b,c; A3b,c;
A4b,c, on the basis that the global population appears to have declined
rapidly, by 30-49% over the preceding three generations, estimated to be
c.34 years, and it is projected to decline by 30-49% over the next
three generations. As noted in the assessment, however, the current
classification is heavily reliant on the extrapolation of small-scale
data, thus large-scale surveys are needed to confirm this
categorisation.

The current trend estimate is based on recorded local declines.
Populations on South Georgia and Bouvet Islands probably increased
substantially in the 1960s and 1970s, but have subsequently decreased.
Study populations on South Georgia declined by 65% from 1986 to 1998 (J.
P. Croxall unpublished data), and the overall South Georgia population
probably halved between c.1978 and 1998 (Trathan et al. 1998).
Study populations on Marion Island decreased by 50% between 1979 and
1998. In contrast, populations on Kerguelen increased by c.1% per year
between 1962 and 1985, and subsequent data from 1998 indicated that the
colonies were stable or increasing (H. Weimerskirch per T. Micol in litt. 1999). Populations in South America may be stable, but data are scant.

The validity of the current assessment for this species has been
brought into question by a review by the US Fish and Wildlife Services
(USFWS 2008). Criticism was levelled at the use of trends at small study
colonies to estimate the overall trend for the Prince Edward Islands.
Likewise, the conclusion that overall numbers on South Georgia declined
by 50% in the last two decades of the 20th century was criticised
because it has not been empirically verified in the literature. Although
the species is thought to have undergone a recent decline on Bouvet
Island, there are apparently no current estimates for the population
there. Significant recorded declines in colonies on Marion Island have
also been questioned due to changes in survey methodology, and an
overall decline of 18% in the island’s estimated total population
between 1994-1995 and 2002-2003 is not considered significant by the
USFWS (2008) in the context of small fluctuations in the three
subsequent three breeding seasons. It has also been asserted that the
decline noted on Prince Edward Island between 1976-1977 and 2001-2002,
in which the estimated population fell from c.17,000 pairs to c.9,000
pairs (Crawford et al. 2003) was overestimated, and that the
overall decline on Marion and Prince Edward Islands combined (c.3.4% of
the species’s global population) was 32% between 1979 and 2003 (USFWS
2008).

These criticisms, combined with suggestions that some populations are
stable or increasing, or have unknown trends, suggest that the overall
estimated rate of decline should be reduced for this species. Comments
on the current listing and further information on the species are
requested.

Monday, September 5, 2011

Emperor
penguins fishing at sea and at an experimental dive hole often spend
minimal times on the surface even after dives that last far beyond their
measured 5.6 minute aerobic dive limit.

Researchers from the US
Scripps Institution of Oceanography and the International Coastal
Research Center, Atmosphere and Ocean Research Institute at the
University of Tokyo went to the Antarctic and attached
accelerometer-based data loggers to Emperor penguins diving in the two
different situations to evaluate the capacity of the birds to perform
such dives without any apparent prolonged recovery periods.

In a report of the study published in the Journal of Experimental Biology, the researchers say the penguins regularly remain submerged for up to 12 minutes by carefully managing their oxygen reserves.

Lead researcher Paul Ponganis from the Scripps Institution says penguins
diving from isolated ice holes fuel the dive aerobically for the first
5.6 minutes and supplement the remainder of the dive with anaerobic
metabolism.

But when the researchers compared the aerobic dive limit for ice hole
diving penguins with estimates of the aerobic dive limit for freely
foraging animals, it appeared the free-ranging birds were able to
sustain the aerobic portion of a dive for up to eight minutes. From the
data loggers, they could see a surge every time the animal strokes with
its wings and they could then count the number of peaks per dive to get
the stroke rate pattern.

"We expected that stroke rate would be lower in dives at sea and because
of that there would be less muscle work and less oxygen consumption and
that would explain how these birds dive as long and as frequently as
they do," Ponganis says. But the freely diving birds were stroking
faster and were not extending their aerobic dive limit by beating their
wings more slowly to conserve oxygen.

When the researchers compared the length of time spent by birds at the
surface recovering from dives, the free divers spent no more time at the
surface than the ice-hole divers.

Assuming the penguins did not exhale while submerged, they found the
penguins carried more air as they extended their dives down to 300
metres, apparently anticipating how deep they would dive and adjusted
the amount of air they carried down accordingly.

Yet penguins that dived 400 to 500 metres appeared to be carrying less
air than the birds that only dived to 300 metres, leading Ponganis to
conclude that they probably exhaled prior to the final segment of the
dive.

On one occasion, the researchers recorded a dive where an emperor
penguin remained submerged for a record-breaking 27.6 minutes although
after it emerged from the water, the bird lay on the ice for six minutes
before it stood, took another 20 minutes before it started walking and
then waited a further eight hours before going back into the water.

Ponganis says the penguin was exhausted and believes the dive was
extended when the pack ice shifted above the penguin's head, blocking
its escape route. That it survived is a measure of the bird's remarkable
capacity to conserve oxygen under water.